The invention relates to a method of installing friction clutches in motor vehicles, particularly on the flywheels which are carried by the output shafts of engines for motor vehicles.
In accordance with a heretofore known proposal, the clutch plate and other parts (hereinafter called housing) of a friction clutch are attached to the flywheel on the output shaft of an engine, while the engine is supported on the conveyor or conveyors of the assembly line, by resorting to a centering tool in the form of a mandrel having a profiled portion which is complementary to the hub forming the axially apertured control part of the clutch plate. A front portion of the mandrel extends beyond the hub of the clutch plate and is insertable into a pilot bearing in the crankshaft of the engine. The next step involves withdrawal of a clutch plate from a receptacle and the mounting of the thus withdrawn clutch plate on the mandrel so that the clutch plate surrounds the mandrel behind the front end portion which extends into the pilot bearing of the crankshaft. This centers the clutch plate with reference to the flywheel which is affixed to the crankshaft. The housing and the diaphragm spring therein are then withdrawn from a second receptacle, and such parts of the friction clutch are slipped onto the mandrel so that the housing is adjacent the flywheel. The crankshaft carries centering pins which extend into compelementary bores or holes of the housing before the housing is threadedly connected with the flywheel. The mandrel is withdrawn in the next step while the clutch plate and its hub remain in a position of coaxiality with the pilot bearing. The final step involves attachment of the variablespeed transmission; to this end, the input shaft of the transmission is introduced into the hub of the clutch plate as well as beyond such hub, i.e., into the pilot bearing of the crankshaft.
In accordance with another prior proposal, the front end portion of the centering mandrel is inserted into the pilot bearing of the crankshaft and the entire friction clutch including the clutch plate and the housing with its diaphragm spring and pressure plate is slipped by hand onto the thus positioned mandrel. The next step involves fastening the housing to the crankshaft and to the flywheel on the crankshaft, normally by means of threaded fasteners. In order to facilitate manual placing of the friction clutch onto the centering mandrel, the clutch plate and the housing of the friction clutch are preassembled into a package wherein the clutch plate and the housing (with the diaphragm spring and the pressure plate therein) are properly centered relative to each other. The last step includes extraction of the mandrel from the friction clutch and from the pilot bearing in the crankshaft so that the hub of the clutch plate and the pilot bearing are ready to receive the input element of the variable-speed transmission.
In accordance with still another presently known proposal, the clutch plates and the housings (with the diaphragm springs and pressure plates therein) are withdrawn from discrete receptacles and are placed onto a conveyor belt in such a way that each clutch plate overlies a housing. The thus obtained packages, each of which contains a clutch plate and a housing, are then grasped by hand and slipped onto centering mandrels.
A drawback of heretofore known methods of assembling friction clutches with the output shafts of engines for motor vehicles is that it is difficult to properly hold a clutch plate and a housing (with a pressure plate and a diaphragm spring therein) and to jointly slip such parts onto a centering mandrel. It has been found that the fingers which are used to grasp the parts of the friction clutch are in the way during placing of such parts onto the centering mandrel.
In order to overcome the above discussed drawbacks of heretofore known methods of assembling friction clutches with the output elements of engines in motor vehicles, a further proposal includes assembling successive discrete clutch plates and successive discrete housings (with pressure plates and diaphragm springs therein) on discrete centering cores. The thus obtained subassemblies are stored in a receptacle and are placed, one after the other, onto a conveyor in an assembly line. Each mandrel includes a first centering portion which serves to center the clutch plate with reference to other parts of the friction clutch. The mandrel further includes an end portion which is located at one end of the first centering portion and serves to enter the pilot bearing in the crankshaft of an engine, and the mandrel further includes a second centering portion at the other axial end of the first centering portion to serve as a means for centering the radially inwardly extending prongs of the diaphragm spring in the housing. Still further, the mandrel includes a fourth portion which is used as a handle and is outwardly adjacent the second centering portion. The second centering portion includes a first section which is surrounded by the tips of prongs forming part of the diaphragm spring, and a second section which is adjacent one side of each tip. Still further, the mandrel includes a hook-shaped retaining or holding portion which engages the hub of the clutch plate. The just described mandrel ensures that the clutch plate and the housing (with the pressure plate and diaphragm spring therein) are properly centered relative to each other and can be more conveniently manipulated as a unit. The worker at the assembly line grasps the handle (fourth portion) of the mandrel and inserts the end portion into the pilot bearing to thus center the parts on the mandrel with reference to the flywheel on the crankshaft. Such centering is followed by fastening of the housing to the flywheel and thereupon by extraction of the mandrel. Extraction necessitates the exertion of a certain force in order to disengage the hook-shaped retaining or holding portion from the hub of the clutch plate. The extracted mandrel is discarded or is returned to the manufacturer of friction clutches. A drawback of the just described method is that it contributes significantly to the cost of the power train in which the friction clutch is installed.